Wood comminutor



May 26, 1970 B. MAIER 3,514,044 WOOD COMMINUTOR Filed June 26, 1967 ISheets-Sheet 1 Fig.7 75 22 24 22b 22a 23 Inventor:

Barri/4s MA/EA? 7 13. MAIER woon COMMINUTOR May 26, 1970 5 Sheets-Sheet2 Filed June 26. 1967 May 26, 1970 B. MAIER ,0

WOOD COMMINUTOR 5 Sheets-Sheet 5 Filed June 26. 1967 B. MAIER WOODCOMMINUTOR May 126, 1970 5 Sheets-Sheet 5 Filed June 26, 1967 vm mm mmmm mm mm 0mm mm United States Patent 3,514,044 WOOD COMMINUTOR BalthasMaier, Brackwede, Westphalia, Germany, as-

signor to Dr.-Ing. Gerhard Maier, Brackwede, Westphalia, Germany FiledJune 26, 1967, Ser. No. 648,671 Int. Cl. B02c 18/00, 19/00; B07b 7/06US. Cl. 241-51 7 Claims ABSTRACT OF THE DISCLOSURE The present inventionconcerns an apparatus for cutting material, especially wood, by means ofa revolving device which feeds the material to surrounding cutters bycentrifugal action.

Devices are known in the form of cutter shafts or disc cutters which cutround timber. Although these cutters produce a good fiat shaving ofuniform thickness, they are unsuitable for cutting up odd wood shapes,such as chips, off-cuts or the like.

Cutting machines are known which are fed with wood waste, such as chips,and which further cut up these chips.

Such cutting machines operate with stationary or rotatable cylindricalcutter cages, in which the wood chips are thrown against the cutter cageby means of a centrifugal wheel acting due to centrifugal force.

In this case the wood chips are only partially out since a proportion ofthe chips is crushed between the centrifuge wheel and the cutter cage.Here the cut material discharged from the cutter cage contains a largeporportion of undesired crushed material, which in the chipboardindustry does not conform to their requirements of narrow, elongatedchips of constant thickness.

Further known embodiments of cutters operate with beaters swingingpendulum-fashion instead of the centrifuging wheel, or with a revolvingcutter cage and fixed feed device. Such hitherto known devices forcutting material, especially wood, have considerable disadvantages,since the supply of the material to be cut results in a vortex formationin the region of the cutters, so that the material is cut irregularlywhich has an adverse effect on the quality of chip and increases theproportion of dust in the final material.

It is an object of the present invention to provide an apparatus forcutting material, especially wood chips or the like, the feed device ofwhich is so formed that by using centrifugal force the material is feduniformly and Without vortex formation to the cutters with a simpleoperating procedure which produces small flat chips of uniform andadjustable thickness.

In accordance with the present invention an apparatus for cuttingmaterial such as precomminuted wood or the like, having a centrifugaldevice feeding the material to a plurality of cutters, in which thecentrifugal device comprises feed passages of turbine form between aplurality of blades located at spaced intervals, which discharge thematerial against the cutters of a fixed cutter cage enclosing thecentrifugal device.

In a preferred embodiment the passages are hydrodynamically shaped andflared in the direction of their ends;

3,514,044 Patented May 26, 1970 'ice the input ends of the passages maybe located on a conical generating line, and towards the output ends maybe bent over at right angles. The ends of the passages are enlargeduntil their orifice is flush with the cutting blades. The blades of thecentrifugal device may be secured to a rotary cage.

According to a feature of our invention the cutting blades may bedetachably mounted on a cutter cage adapted to be interchangeable as awhole, and are arranged on a plane; alternatively the cutters may bearranged on a frusto-conical surface to one another, or may be mountedalong the surface of a cylinder. The rotary cage may be mounted for cutadjustment so as to be axially displaceable relative to the cutter cage,and the cutters pitch blades may be individually adjustable for chipthickness in the cutter cage, though the cylindrical cutter arrangementis not so adjustable.

The outer surfaces of the cutter cage in the region of the cuttingblades may be case hardened, the hardening being provided by hard metalapplied or sprayed thereon, or by nitridin-g the surface.

This apparatus in accordance with the persent invention feeds thematerial to be cut to the cutters by centrifugal action whilstminimizing vortex formation and has a uniform feed action with lowfriction. The feed device has the form of a pump impeller which isconstructed hydrodynamically for coarse-grained material, and theimpeller-type blades have an excellent conveying action.

The construction of the feed device used provides a constant rate ofcutting the material charged, since even with a partial charge thematerial remains pressed against the cutter cage without vortexformation until cut up completely, since the guidance of the spatiallycurved blades acts like a pump for the pieces of wood.

Furthermore the cutting effect takes place over the whole width of thecutters, and the cut material is discharged over the whole outletcross-section without any tendency to vortex formation.

The invention will be described further, by way of example, withreference to the accompanying drawings, in which:

FIG. 1 is a vertical section through a pair of disc cutters having afrusto-conical cutter arrangement and feed blades;

FIG. 2 is a partial section through a modified pair of disc cutters witha flat cutter arrangement and feed blades;

FIG. 3 is a view of the cutter arrangement as shown in FIGS. 1 and 2;without the cutter cage;

FIG. 4 is a vertical section through a modified pair of disc cuttershaving a cylindrical cutter arrangement;

FIG. 4a is a partial view of the same cutter as shown in FIG. 4, and

FIG. 5 is a cross-section through a cutter cage with adjusting means forthe cutters.

In FIG. 1, a machine frame supports a pedestal bearing 11 and a sealingcover 12, with a horizontal driving shaft 13 which rotates a cage 14with external guide blades 15 for the material to be cut. On thisdriving shaft 13 a V-pulley 16 is splined, which is rotated by means ofa driving belt, not shown. The cage 14 is supported by a plurality ofroller or ball bearings 11, 17, 18 which are mounted on a shaft 19 whichis rigidly connected with a face plate 19a in turn secured to themachine frame 10.

The machine frame 10 has a dished housing 20, and between this and thesealing cover 12 there is a charging hopper 21 which discharges into thepassages 15a of the guide blades 15.

These passages 15a are flow-curved like the blade passages in pumpstowards a cutter cage 22, which is clamped between the housing 20 andthe face plate 19a. The

3 cage carries separate cutter head supports 22a for the cutting blades22b and the stump cutters 63 (FIG. 5). The passages a are flared, withtheir orifices flush with the cutting edges of the cutting blades 22!).

The rotary cage 14 with the blades 15 is designed along the lines of apump impeller, so that the surfaces of the blades 15 form an acute angleat the cage outlet with the conical surface of the cutter cage 22,whereby during rotation, the material to be cut is then firmly pressedagainst the cutting blades 22b, even when the machine is only partiallyloaded.

With such partial loading, i.e. in which the material supply does notcompletely fill the blade passages, and to ensure even distribution overthe whole length of the cutters, rib plates 25 may be provided on thewheel outlet in the peripheral direction of the rotary cage 14, arrangedin the direction of feed, the plates being secured alternately on therear side of one blade 15 and the front surface of the adjacent blade15; these rib plates 25 divide the outlet cross-section of each passage15a into two or more rectangles seen along the conical generating line.In this way, when the passages are not filled completely, pieces ofmaterial which strike against the inner part of the cutter'cage 14 areprevented from slipping outwards due to the centrifugal force along thecone generating line on the cutter cage 14, thus ensuring asubstantially uniform distribution of material to the cutting blades22b.

To vary the thickness of chip cut, the distance of the inner rotary cage14 from the cutters may be varied in the direction of its pivotal axis.For this purpose, adjusting screws 26 engage the face plate 19a andcarry gear wheels 27 on their outwardly projecting ends which arerotated by means of a large gear wheel 28, rotated by a hand wheel 29.The screws 26 press against a displaceable thrust ring 30 on the faceplate 19a and thereby displace thrust bearings 32 between the face plate19a and the rotary cage 14 and hence move this rotary cage 14 in thedirection of the pedestal bearing 11, so that the gap between theorifices of the passages 15a of the blades 15 and the cutting edge ofthe cutting blades 22b is increased. This displacement takes placeagainst a disc spring 31 which is supported at the end of the journal 19against a screw 31a and which, when the screws 26 are slackened, urgedthe rotary cage 14 into the opposite direction, thus causing the saidgap to be reduced.

It is also possible to effect the adjustment of the rotary cage 14 in anaxial direction by means of a spindle structure, in which by turning ascrewed spindle to the right or left, the rotary cage 14 is forwardly orrearwardly displaced, and remains so positionedi Owing to the feedaction of the rotary cage 14 acting as pump impeller, the flat chipshurled through between the cutting blades 22b are discharged into a ringchamber 23 which is covered by an external removable cylinder housing 24adjacent to the dishlike housing 20. Due to the feed pressure producedby the rotary cage 14, the cut material is progressively conducted awayfrom this cylinder housing 24 via a pipe socket 33, and the feed actionmay be assisted by an extractor fan (not shown) into which a deliverypipe 34 leads.

In the modified embodiment of a disc cutter shown in FIG. 2, the cuttingedges of the cutters 41 are located on a plane so that the orifices ofthe passages 42 of the guide blades 43 sweep over an annular ringsurface. This is the limiting case of a conical cutter cage with 90taper; a flat surface studded with cutting blades 14 is thus obtained.

This embodiment uses the remainder of the features of the embodimentdescribed with reference to FIG. 1; it differs only in that in thecutting operation, perfect chips are formed as in conventional flat disccutters; in this case also the feed action is used for the shreddingmovement. The chips to be shredded are supported substantially flat onthe cutter surface. This embodiment is particularly economical in cost.

FIG. 3 shows the shapes of the blades 15, with the blades 15 in fulllines and with passages 15a according to the embodiment of FIG. 1, thebroken lines showing the blades 43 with passages 42 of the embodiment ofFIG. 2. The blades 15, 43 are either curved in a peripheral direction(arrow A) or bent sharply as with turbineblades; they are flared outwardto avoid jamming.

In the modified embodiment shown in FIG. 4 a frame 45 supports apedestal bearing 46 and a closure cover 47 in which shaft 48 isrotatably mounted. This shaft 48 is rigidly connected with a rotary cage49 which is mounted on a steel-shaft 50 by means of bearings 51, theshaft being carried in a face plate 52. In this embodiment the passages53a facing radially outwards of the pump-like curved blades 53 areenclosed by a cylindrical cutter cage 54, the cutters 54a of which arehence parallel to the horizontal shaft 48. In this case the limit of thecone angle is 0, i.e. the cutters 54a extend parallel to thelongitudinal axis of the shaft. The chips arriving from the charginghopper 55 are subject to considerable deflection in the passages 53a andare thereby aligned and then urged at an acute angle against the cutters5411, the feed action of the pump-like rotary cage 49 being particularlyadvantageous.

The chips produced in the cutting guides described above with referenceto FIG. 4, are collected in an outer ring chamber 56 from whence theyare extracted by suction.

A further feature of the invention consists in that in all embodimentsthe cutting blades with their cutter head supports are assembled into acutter cage, which may be removed from the cutting device for regrindingthe cutters, or may be changed for a cutter cage having sharpenedcutters. Such a change is simple and take little time, so that theidling time during changing the blades is minimal.

FIG. 5 shows how the cutting blades 22b are adjustably mounted in thecutter cage 22.

Thus, for each cutter 2212 a flat cutter head carrier 22a is secured onthe cutter cage 22 on which the cutting blade 22b is supported; eachcarrier has a plurality of longitudinal slots 58 parallel to oneanother, through each of which a bolt 59 is inserted.

An adjusting screw 60 engages the rear of the cutter 22b the screw beingmounted on the cutter head carrier 22a by means of a clamp 61 in whichit is threaded. This clamp is a detachable device for cutter adjustment,which is removed after the cutter 22b has been adjusted. For thispurpose the clamp 61 is provided with a rotatable locking closure -62which temporarily fastens the clamp 61 on the cutter head carrier 22a.

If the screw 59 is slackened, then by turning the adjusting screw 60 tothe cutter 22b is shifted forwardly to take up wear. 7

The pitch blade 63 used for the setting gap for the chip thickness maybe adjusted in the same way. For this purpose this pitch blade 63 has aslot 64 through which an adjusting bolt 65 passes to engage in thecutter cage. By slackening this screw '65 the pitch blade may beadjusted. The cutting blades 22b and the pitch blades 63 permitproduction of a very flat chip of, for example, 0.2 mm. to 0.3 mm.thickness. The 'readjustments prevent pieces of wood not fully shreddedfrom being prematurely extracted by suction.

It is advantageous for the surfaces of the cutter cage to be casehardened by nitriding, or covered with hard metal, which may be sprayedon. This prevents these running surfaces from being scored on both sidesof the cutting blades by wood friction. These surfaces must remain flatin order to produce perfectly uniform chips. All machine parts arereadily assessible; the thickness of all chips produced may be adjustedin a simple manner as already described by displacing the rotary cagecarrying the guide blades.

The formation of the rotary cage as a pump impeller,

the adjustability of the spacing between the end of the rotary cage andthe cutting edges of the cutters, the individual adjustability of thecutting blades and the pitch blades, interact to cause the material tocut uniformly conveyed to the cutters without vortex formation, toremain there until completely cut up without small uncut pieces beingextracted by suction; in addition, all size reduction is effected by acutting process and not by crushing.

I claim:

1. Apparatus for producing shavings comprising:

a fixed ring having a plurality of cutters mounted r a frusto-conicalbody rotatably monuted within said means for rotatably driving saidfrusto-conical body; a hopper for receiving precommuted material; and

means forming in a plurality of juxtaposed, curved, and outwardlydirected guiding passages on said frusto-conical body between saidhopper and said cutters, said passages being enlarged towards theiroutlet end to the width of said cutters and the curvature of saidpassages being such that suction is produced during rotation of saidfrusto-conical body to cause said pre-comminuted material to be pressedagainst said cutters.

2. Apparatus according to claim 1 wherein said means forming saidplurality of guiding passages includes a plurality of blades forming thewalls of said passages, said blades being arcuately curved in the samedirection as the direction of rotation of said frusto-conical body.

3. Apparatus according to claim 1 wherein said means forming saidplurality of passages includes a plurality of blades forming the wallsof said guide passages, said blades being monuted at an angle in thesame direction as the direction of rotation of said frusto-conical body.

4. Apparatus according to claim 1 wherein said cutter ring is afrusto-conical body.

5. Apparatus according to claim 1 further comprising a plurality of ribsarranged at the outlet end of said guiding passages to evenly spread thepre-comminuated material over the width of said cutters.

6. Apparatus according to claim 1 wherein said frustoconical body isrotatably mounted on a shaft within said ring.

7. Apparatus according to claim 6 wherein said frustoconical body isfurther slidably mounted on said shaft, the position of saidfrusto-conical body along the length of said shaft determining thethickness of said shavings.

References Cited UNITED STATES PATENTS 2,369,312 2/ 1945 Porteous 241-902,874,909 2/1959 Pallmann 24193 X 2,917,248 12/1959 Krug 241299 X3,219,076 11/1965 Logan 241-93 X 3,371,693 3/1968 Voelskow 241-91 XROBERT C. RIORDON, Primary Examiner D. G. KELLY, Assistant Examiner.

US. Cl. X.R.

